Method of assembling cam followers and valve stems



J. K. SCOTT July 28, 1942.

METHOD OF ASSEMBLING CAM FOLLOWERS AND VALVE STEMS Filed May 23, 1940 INVENTOR. 0W5; /K 5507/? Patented July 28, 1942 METHOD OF ASSEMBLIN G CAM FOLLOWERS AND VALVE STEMS James K. Scott, Richm ican Throttle Compa nd, Va., assignor to Amerny, Inc., New York, N. Y.

Application May 23, 1940, Serial No. 336,768

1 Claim.

The present invention relates to an improved method of joining a cam follower of the stirrup type in swivelling relation to the end of a valve stem.

In multiple throttles such as are used with locomotive superheaters a number of valves are arranged in a line in the superheater header and are operated by individual cams on a rock cam shaft extending longitudinally of the header below and parallel with the line of valves. In one form of mechanism for operating the valves as shown in the patent to Pippy, No. 1,863,063, issued June 14, 1932, the cam for each individual valve extends into the slot of a stirrup member and by engaging surfaces at the ends of the slot raises and lowers the valve. The stirrup member is mounted in swivelled relation on the end of the valve stem so that the valve and its connected parts may be turned for the purpose of grinding it on its seat while the stirrup is kept from turning by the operating cam.

The present invention resides in an improved method of joining the stirrup member in swivelled relation on the end of the valve stem so as to simplify the construction by reducing the number of parts required to mount the stirrup as compared with some earlier constructions.

In the drawing Figure 1 is a longitudinal sectional view through a superheater header having a multiplicity of valves of the type to which the invention is directed.

Figure 2 is a sectional Fig. 1; and

Figure 3 is a sectional view illustrating the manner of applying the stirrup member to a part carried by the valve stem.

As shown in Fig. 1 the superheater header I0 is formed with outer chambers II and I2 separated from an intermediate chamber I3 by partitions I4 and I5 respectively. In the partition I4 are a number of ports I6 arranged in a straight line while the partition I5 is formed with circular openings II alined with the ports I6. The flow of steam from the chamber II to the chamber I3 through each port I6 is controlled by a valve disk 20 carried by a stem 2I which at its lower end is provided with an enlarged head 22 fitting in the related opening I! to guide the movements of the valve.

view on the line 2-2 of for receiving a cam 25 carried by a rock shaft 23 which extends longitudinally through the chamber I2 below the partition I5. As shown in Fig. l the head 22 is threadedly engaged on the valve stem 2I and secured against rotation, as by a pin 21. To raise the valve the cam 25 engages the end of valve stem 2I which projects into the slot 24 of the stirrup member while in lowering the valve the cam engages the bridge piece 30 of the stirrup.

In accordance with the present invention the Associated with each head 22 is a stirrup member 23 having a slot 24 stirrup member 23 is mounted and joined to the end of the valve stem as follows: Before being connected to the valve stem 2| the head 22 is formed with a centrally located recess and an undercut flange 3I at or near the outer end of the recess thus providing an inwardly extending annular lip. The lip provided by flange 3I is adapted to interlock with outwardly extending lip portions 32 at the upper ends of the leg portions 33 of the stirrup 23. It may be seen that the stirrup member 23 is in the form of a U- shaped yoke consisting of spaced legs 33 connected at their lower ends by the bridge piece 30 and having the lips 32 located in diametrically opposed relation at the upper end of the legs 33 and extending outwardly from the outer side faces thereof. To join the stirrup member 23 to the head 22 of the legs 33 of the stirrup are, preferably, heated (as in regions designated A in Fig. 3) and bent inwardly so that the distance between the outer faces of the lips 32 is reduced to a dimension at least as small as the distance separating opposite face portions of the flange 3| on head 22. While the stirrup 23 is still heated, the ends of the legs 33 are inserted in the recess in the head 22 and the legs are then bent outwardly to engage their lips 32 behind the flange 3| on the head 22. The stirrup 23 is thus joined in swivel relation to the head 22 which then may be screwed on to the lower end of the valve stem 2| and held against turning as by the pin 21, or by spot welding the head 22 to the stem 2I in this region.

What I claim is:

The method of joining a cam receiving stirretaining lip; forming a metallic yoke-like stirrup member having two spaced legs joined at one end by a bridge separating opposite face portions of the retaining lip on said head portion; inserting the lip end of said yoke legs in the recess of said head portion; bending said legs outwardly while still heated to approximately said temperature for engaging the lips at the ends thereof with the retaining lip on said head portion and maintain- JAMES K. SCO T, 

